What is Effluent Treatment?
Effluent treatment is a process of removing harmful toxins from the water that is used by hotels, restaurants, resorts, hospitals and industries. It is important to transform the dirty and unhealthy water into the clean and safe water so that the recycled water can meet its quality standards. Major sources of effluent produced from many hotels are: washing of utensils, sink basins and restrooms. About 70-75% of the hotel waste is biodegradable (like food, vegetable and non-veg waste) will get mixes with all other types of non-biodegradable waste (such as suspended solids, oils etc) when disposed at a collection spot.
Why treat hotel effluent?
Today, there are many hotels and restaurants which contribute substantial amount of wastewater/effluent. Hence, treatment of hotel sewage using ETP is essential in order to reduce the spread of disease causing pathogenic organisms in the effluent and to prevent the pollution of surface and groundwater. Treatment of waste water is carried out by a combination of physical, chemical and biological methods to remove suspended solids, organic matter and some nutrients from effluent/wastewater.
It removes all the coarse solids and other materials from the raw wastewater thereby preventing damage of subsequent treatment units. When the influent passes through bar screens, large sized materials like plastic bags, sticks, rags etc. It uses comminutors for breakdown of coarse solids. It may include grit chamber at which velocity of wastewater reduces so that grit, sand and stones will be removed. This treatment also removes desirable amount of oils and greases. The partially treated wastewater is now subjected to the next level of treatment.
This is the second level in most of the ETP’s. It involves physical separation of total suspended solids. It involves a tank called sedimentation tank or primary clarifier where heavier solids settle to the bottom and floatable materials (scum) like oil, grease will rises to top of the tank and removed by skimming process. The effluent from primary sedimentation tank is referred to as primary effluent or primary sludge. This sludge will be subjected to sludge handling facilities for further processing. This treatment removes about 50-70% of total suspended solids and about 30% of the biodegradable components.
The major purpose of secondary treatment is to decompose suspended and dissolved organic matter in wastewater using microorganisms. To achieve this it uses aerobic biological treatment process called activated sludge process. Now the influent is allowed into aeration tank where it is mixed with microbes. Air is continuously supplied to aeration tank to increase the growth of microbes and hence breakdown of organic matter takes place. When aerated water flows into secondary clarifiers where heavier particles settle to the bottom which is called as secondary effluent. It removes about 70-80% of organic solids.
This level of treatment is also called as disinfection treatment. If the treated wastewater from secondary tank contains residual suspended solids or organic matter then tertiary treatment uses physical or chemical or biological processes to remove them. It is the final cleaning process that improves quality of waste water before it is discharged into natural water courses or reused or recycled. It uses some disinfectants like chlorination, UV light, ozone etc. where UV is the most using disinfectant which kills viruses and bacteria without any residues. Disinfection is essential step which protects the health of human and environment.